Which structure is described as a concrete barrier across a river that creates a small waterfall and aids in aeration?

• A. Wellington Street Dam
• B. Water Level Indicator
• C. Weir
• D. Pond Creek

Answer: (C)

A weir is a barrier built across a river that makes water spill over its top, producing a small, visible waterfall. That flow over the edge creates turbulence and pulls air into the water, which aerates it and increases the dissolved oxygen. This same structure sits across the river to regulate flow and often raises the water level upstream just a bit. The other options aren’t barriers designed to produce a controlled drop and enhanced aeration: a dam is usually larger and used for storage, a water level indicator is just a measuring device, and Pond Creek refers to the stream itself, not a crossing barrier.